1. Field of the Invention
This invention relates to a machine for applying a screw cap to a container. More particularly, this invention relates to high speed capping machines in which a screw cap is screwed onto the threaded neck of a container.
2. Description of the Background Art
Presently, there exist several basic types of capping machines utilized in the packaging machinery industry. The most prevalent type of capping machine is commonly referred to as "continuous rotary motion screw cappers". These rotary motion screw cappers typically consist of a main turret, or carousel, having a plurality of rotary and vertically reciprocating chuck spindles positioned about the periphery of the main turret. A supply of screw caps, properly oriented, are fed into a cap star wheel whose pockets are positioned in tangential alignment with the chuck spindles. Similarly, a supply of containers, having been filled with the product to be packaged, is fed into a container star wheel and then transferred into a main star wheel whose pockets are positioned in concentric alignment with the chuck spindles of the main turret. During operation, the chuck spindles sequentially engage and lift a screw cap from the cap star wheel and then, upon further rotation of the main turret, the chuck spindles are spun and moved downwardly until the screw caps engage the threaded neck of the container. As each screw cap has been properly torqued, the chuck spindle is moved upwardly, and the cycle is repeated. To accomplish proper torquing, the chuck usually either consists of a friction clutch device which begins to slip when proper torque is obtained or a cocked spring or torque-sensitive trigger mechanism having jaws which snap open to release the cap when the preset torque is obtained.
It is noted that the requirement that the chuck spindles vertically reciprocate significantly contributes to the complexity of the screw capping machine. One attempt known to Applicants to reduce the vertical reciprocating travel of the chuck spindle is disclosed in British Patent Specification No. 735,444, published Aug. 24, 1955, and entitled "Improvements and/or Relating to Arrangements for Spinning Caps on Cylindrical Objects Such a Bottles". In said British patent specification, there is disclosed a vertically reciprocating plunger on which rests the containers to be capped. During operation, the plunger is forced vertically into engagement with the spinning chuck spindle for engagement with the screw cap to be threaded onto the threaded neck of the container. Further upward movement of the plunger then forces the chuck spindle vertically upward to properly torque the screw cap onto the threaded neck of the container. Russian Pat. No. 721,371, published Mar. 15, 1980, discloses a pivotable-type plunger which forces the container upwardly for engagement into the chuck spindle while allowing the plunger to slightly pivot or tilt when the neck of the container engages the chuck spindle.
From the foregoing, it should be appreciated that there exists a need in the bottle capping industry for a bottle capping machine which does not require vertical reciprocating motion of the chuck spindles during the entrainment or pick up of the screw caps or during the threading of the screw cap onto the threaded neck of the container. Such a need, if satisfied, would significantly reduce the complexity of the screw capping machine and result in increased throughput and reliability, all at a reduced cost to the packager.
Therefore, it is an object of this invention to provide an apparatus and a method which overcomes the aforementioned inadequacies of the prior art devices and methods and provides an improvement which is a significant contribution to the advancement of the screw capper art.
Another object of this invention is to provide a screw capper for screwing a screw cap onto the threaded neck of the container by means of a non-reciprocating chuck spindle.
Another object of this invention is to provide a screw capper which is operable at relatively high speeds to enhance the throughput of the machine at a cost savings.
Another object of this invention is to provide a screw capper for screwing a screw cap onto the threaded neck of a container in which only the screw caps and the containers are moved vertically upward for engagement into the chucks of the chuck spindles of the screw capper.
The foregoing has outlined some of the more pertinent objects of the invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the intended invention. Many other beneficial results can be obtained by applying the disclosed invention in a different manner or modifying the invention within the scope of the disclosure. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description of the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.